Exposure to common urban air pollutants in the first year of life is associated with a higher burden of respiratory infections and wheezing, according to a longitudinal study led by the Precision Vaccines Program at Boston Children’s Hospital. The findings were presented late last week at the Pediatric Academic Societies 2026 Meeting in Boston. 

The analysis, which looked at data from infants enrolled in the Immune Development in EArly Life Rome cohort, found that greater cumulative exposure to particulate matter (PM₁₀), nitrogen oxides (NOₓ), and nitrogen dioxide (NO₂) was tied to more frequent physician-diagnosed respiratory infections during the first year of life. Infancy is a critical window for immune system development, and airborne pollutants are increasingly recognized as potential immune-system disruptors.

the air infants breathe during the first year of life affects not only lung health but may also permanently influence the development of their immune defenses.

“We observed a clear and significant association between common urban air pollutants and a higher incidence of respiratory infections and wheezing,” lead author Donato Amodio, MD, PhD, assistant professor of pediatrics at the University of Rome Tor Vergata and a staff physician at Bambino Gesu Children’s Hospital, told CIDRAP News. “Our findings suggest that the air infants breathe during the first year of life affects not only lung health but may also permanently influence the development of their immune defenses.” 

The researchers clinically evaluated infants at ages 2, 5, 9, and 12 months and conducted phone follow-ups. The team recorded physician-diagnosed respiratory infections and wheezing episodes and estimated pollution exposure by linking each infant’s residential postal code to nearby government air-quality monitoring stations.

Cumulative exposure to PM₁₀, NOₓ, and NO₂ was calculated at each time point. Higher exposure levels were consistently associated with more recurrent respiratory infections. The strongest correlation was observed for PM₁₀, followed by NOₓ and NO₂. Similar patterns were seen for wheezing, though the associations were more modest.

Individual infections, including bronchiolitis, bronchitis, acute otitis media (ear infection), COVID-19, and tonsillitis, showed statistically significant but weaker correlations with pollutant exposure.

While the authors say more research is needed to clarify how poor air quality may impair infants’ immune defenses, the findings add to a growing body of evidence indicating that ambient air pollution increases susceptibility to respiratory infections. The data also point to a potentially modifiable risk factor for preventing early-life respiratory illness. 

“This research highlights the urgent need for environmental protection measures to safeguard children during the most critical stages of their development,” says Amodio.